Efficacy of Neem and Eucalyptus Leaf Powders for the Management of Maize Weevil Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) in Dried Sweet Potatoes

Maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) is a polyphagous storage pest in many crops of economic and food security importance. Its management currently relies mainly on synthetic chemical pesticides. However, plant botanicals are known to exhibit insecticidal properties which can be used to manage the weevil in stored dry sweet potatoes. To study the effect of neem and eucalyptus leaf powders, an experiment was set up at Busitema University laboratory. Neem and eucalyptus leaves were processed into powders. 400g of dried sweet potato chips were weighed and placed in 4 different plastic buckets. Under laboratory conditions, buckets were inoculated with 30 unsexed newly emerged adult weevils. To each bucket, 40g of leaf powders were introduced as single powders and a combination. The experiment was replicated three times. Data on mortality, growth inhibition, produce damage and weight loss was collected over a period of 84 days. Analysis of variance showed that all plant powders showed significant (P<0.001) increase in mortality and inhibition of maize weevil and a decrease in damage and weight loss of sweet potato compared to control. The combination showed superiority in all parameters measured. Effectiveness of the plant powders was in the order; combination (neem + eucalyptus) > neem leaf powder > eucalyptus leaf powder.